Hillary Clinton has hit out at rival Donald Trump in a strongly-worded attack, saying the presumptive Republican nominee is "not qualified" to be president of the United States.

In an interview with CNN, the Democratic front-runner questioned Mr Trump's ability to handle complex foreign policy challenges, decrying what she described as his "irresponsible, reckless, dangerous comments".

She cited recent comments from Mr Trump criticising Britain, praising the leader of North Korea and questioning America's membership of Nato.

She said she knows "how hard this job is", and added that she has "concluded he is not qualified to be president of the United States".

Looking ahead to the general election, Mrs Clinton asserted that she "will be the nominee" for the Democratic party, noting her lead in delegates and votes over her opponent Bernie Sanders.

"That is already done in effect. There is no way that I won't be (the nominee)," she said. She is currently 90 delegates short of clinching the nomination, though Mr Sanders continues to win contests and has vowed to march on to the Democratic convention in July.

On divisions among Democrats, Mrs Clinton said she is committed to party unity, but she argued that Mr Sanders will also have to play a role in bringing Democrats together.

She recalled that in 2008, after losing the primary to President Barack Obama, she endorsed him and campaigned for him.

"Whatever differences we may have, they pale in comparison to the Republican nominee," she added.

Asked if she should reach out to Mr Sanders to work things out, Mrs Clinton said: "I am absolutely committed to doing my part. But Senator Sanders has to do his part."

She declined to say whether she has considered Mr Sanders for her running mate if she wins the nomination.

Mrs Clinton said she is ready to take on Mr Trump, but vowed to keep the conversation focused on issues and her record, rather than personal attacks.

"He can say whatever he wants to say," she said, later adding that if "you pick a fight with a bully, you know, you are going to be pulled down to their levels".

Mrs Clinton said she would not engage with Mr Trump when he takes shots at her husband, former president Bill Clinton.

"No, I know that that's exactly what he's fishing for. I'm not going to be responding," she said.

Mrs Clinton also spoke about EgyptAir Flight 804, which crashed into the Mediterranean Sea early on Thursday, saying it "does appear it was an act of terrorism" and that it "shines a very bright light on the threat that we face".